Having been surrounded almost all my life by people with a not-so-rare condition called "persistent and chronic tardiness," I've become a sort of expert on deciphering their language. In case you are wondering -- your boss at work who keeps you later because he didn't get there until 10, or that friend who rolls up at 5:30 when you were supposed to meet at 5 -- these people aren't going to change. They're not going to wake up one day and think, "I'd like to make an improvement in my life that will directly and positively affect the most people around me. I know, I'll start being punctual!" No, these people will probably be late for their own funerals. So the best way to deal with them is just to learn their language.

That said, here are a few common expressions of the chronically tardy, and their translations for the rest of us:

"I'm on my way."
...means...
"I'm thinking about leaving in the next half hour. And yes, I know I was supposed to be there an hour ago."

"Why don't I swing by later?"
...means...
"At one point I intended to make it there at the specified time, but as soon as I got out of bed this morning I knew it would be a wash."

"Wait, what time does this start?"
...means...
"I know the event is already over. I'm not coming."

"I'm just heading out the door now."
...means...
"I just woke up."

"I just need to finish a few things up and I'll be there. 10 minutes, tops."
...means...
"There are approximately 6 stops I have to make before getting to you. And they're all over town."